whole lamb on a spit

I'm going to hire a grill specialist to grill a whole lamb on a spit for an event in a couple months time. While I've eaten this before (and loved it!) I'm not really sure what sort of questions I should be asking potential vendors, to suss out if they're producing a superior 'lamb-on-a-spit' experience.

I'm imagining coal is better than a gas grill, and my butcher says butterflied whole lamb tends to have a better ratio of crispiness to moistness. He also said to avoid people who carve and then reheat the meat, although all the websites I've looked at so far indicates that pretty much everyone does this.

I totally agree, Joe, but unless someone was totally incapable, can you trust a stranger to know the difference between okay lamb and superb lamb? That's why I'm focusing so much on their techniques, since stuff like gas vs charcoal is pretty easy to make a decision on.

I agree about the butterflying. Whilst cooking pigs on a spit is commonplace, I've actually never seen anyone do a lamb. The nearest way was to butterfly it and then it was tied to a metal cross - each limb of the lamb* being tied to limb of the cross. It was cooked by the cross just being stuck in the ground in front of the fire. Was delicious as I recall.